[solved] keys jittering...

[Eszett]

Hi makers! On my recent build I have some keys "jittering", to be more specific only those keys in row6 and row7. I replaced all diodes in these rows by new ones which unfortunately didn't solve it. Does someone have a clue what could be the issue here? Here I'm trying to visualize my problem:

[vvp]

It does not look like a diode problem. It looks like you have a intermittent short between row6 and row7 wires. Or a fixed resistance between those wires is not infinite but around the pull(up/down) resistor resistance.

[Eszett]

vvp! Alright, I checked the pins of the Atmega with a microscope but couldn't see any suspicious solder lumps which could create a bridge. However, I took my soldering iron and reflowed the solder joints anyway. God in heaven, that solved it! The lesson I learned is, that I can't even trust my 300x microscope, since lumps may hide between the pins at spots and angles where my magnifiers/microsopce can't see. My alternate theory is, that I forgot cleaning with Isopropyl (yes, I did), and little solder paste balls created a semi-bridge between the pins? Can that be? Anyway, keyboard hail!

[Darkshado]

Isopropyl would be good for excess flux, not so much for bridging. I haven't done much surface mount yet, but one trick I'd suggest is using soldering wick on top of the contacts to remove excess solder and potential bridges.

[vvp]

If it was SMD then it could be some soldering paste which was not melted and created a (high resistance) connection between the two pins. Or it could be other things. Hard to tell without detailed pictures. And even with the pictures we just may not know.

[Eszett]

Ah alright... now. Marked the thread as [solved]